Invisible, Underground HVDC Power Costs No More Than Ugly Towers

Clean, renewable power is running into transportation problems. To deliver renewable power from remote areas to where the people need it, we need to add a lot of transmission capacity to the grid. If we follow our traditional practice of building ugly towers all over the landscape and stringing wires from them, we will spend years fighting environmentalists only to ruin the landscape we love.

The U.S. power industry is very slow to change. In 1954 Sweden began using High Voltage DC (HVDC) power transmission instead of the AC system, which was created in 1885 by Nikola Tesla. DC systems used to be much more expensive because expensive electronic voltage converters had to be used in place of simple transformers. However, semiconductor costs are falling while transformer, land and steel costs skyrocket. As a result, underground HVDC power transmission is rapidly becoming cheaper than ugly AC towers. By following existing road and rail rights of way, very quick turnaround times are possible and court battles are avoided.

Credit:ABB Ltd., Zurich, Switzerland

AC power transmission requires 3 cables instead of two and has additional losses due to skin effect and capacity to the ground. DC voltage converters are very efficient with less than 1% loss. They also handle faults much better as they can respond in an instant. They are already used to tie together our regional AC grids.

Most regulated utilities have little incentive to cut costs as they are given a percentage as their profit. Los Angeles is one exception. The LA Department of Water and Power serves the ratepayers, not shareholders. LADWP built one of the few long HVDC links in the U.S. in 1986. It brings 1600 megawatts (MW) of power from Utah to Los Angeles. The link is now being upgraded to 2400 MW and will soon be extended to the wind farms in Wyoming.

Wyoming wind is very valuable in Los Angeles because wind peaks in the evening, hours after electrical demand peaks in the afternoon. The two-hour shift in sun position between Los Angeles and Wyoming causes wind output to almost perfectly match electrical demand. HVDC power links pay for themselves quickly because the spot price of electricity varies by as much as 3:1 through the day and can be mismatched by as much as 33:1 between unconnected areas.

Wind power that has no place to go can actually have a negative value, as it must be disposed of. Solar power in the north requires links to southern deserts, preferably further West as solar output peaks about four hours before demand peaks. North-South links between populated areas also smooth annual demand variation: In the north, demand peaks in Winter while the south needs more in summer for air conditioning.

HVDC links should be built to link rich renewable resources to distant population centers. Solar thermal plants in the Sahara desert and the hydroelectric resources of Scandinavia could power all of Europe. The current system of importing energy through pipelines, trains and tanker ships should be replaced by clean, efficient HVDC power links. An excellent movie on the subject by GENI is called "There is no energy crisis; there is a crisis of ignorance"

HVDC connection losses are only about 3% per 1000 km plus 1.5% for two voltage converters. This is much more efficient than conventional transportation. In fact HVDC can be often be justified because it is cheaper than building a pipeline to bring in gas to run power plants. Electric motor efficiencies are typically above 90% while fossil fuel engines are usually under 30% so it is more economical to ship electricity than fuel. 80% of rail shipping in the U.S. is for transporting fuel.

The United States has been completely left behind in HVDC equipment development. Swedish, German, French and Japanese companies dominate the field and have built an extensive network of links. Many are across the waters surrounding the continent. The U.S. needs to play catch-up. We clearly need new laws that encourage grid development in the U.S. to accommodate our renewable energy.

Superconducting cables are even more promising but still too expensive. American and Japanese companies have already installed working superconducting links. With superconductors there is no loss in the cable but the wire must be kept cold with circulating liquid nitrogen. Newer superconductors under development can work at dry ice temperatures but much development is needed.

As with many of our energy problems, the technical solutions are the easy part but the regulatory environment is the real problem. Subsidy decisions made decades ago distort the market and encourage continuation of the inefficient fossil-based status quo. New laws could make it easier and more profitable to build HVDC links and greatly reduce the cost of renewable energy.

21 Comments

What about running lines made by (CPTC) Composite Technology Corp.they are very efficient and have almost no line loss,and also carry more power than your average HVDC line.
These new lines should be run along the pipeline that comes from Nova Scotia down into Southern New England. We should not have these near residential areas where they could be dug up.

Now Warren, it should be obvious that I only brought up uranium in the above discussion to point out that any estimate of the cost of transporting fuel depended on factors such as the mass of the fuel and the energy the fuel produced and thus that Tom's argument had a flaw. However, I will remark that nuclear power certainly does not cost more than 14 cents/kWh, is not heavily subsidized by the government (on a kWh basis "subsidies" even including research, which I would not call a subsidy, are much less than a 1 cent per kWh), and it isn't dead. Lots of new reactors are being built--just not in the US. Perfect options for power generation do not now exist, and given the concerns about atmospheric CO2 concentrations, nuclear clearly remains on the table. Designing an energy generation system entirely from renewables that can be built in what could be the needed time frame and at an affordable cost isn't something we are able to do yet.

Yes, there is an advantage in HV-DC voltage transmission over that of HV-AC. Tom Edison, the great inventor, realized that in the transmission of DC over AC it gave 5% more power at the end of the line.
Even converting the AC power to Hydrogen (via electrolysis) and pumping it 1,000 mi. and converting back to AC loses less energy than straight AC transmission. There is a huge line loss for that distance.

Great article ! My company will use an underground HV-DC pipeline to the nearest "ugly" grid tower. I hope you can convince SDG&E to build underground their proposed Sunrise grid link ! This would eliminate any "stake holders" criticism of the tower grid link.

Scott: No, electromagnetic radiation transfer through soil is not a problem.

Steven:

Let me put the final nail in nuclear power's coffin. As an ex-nuclear engineer for GE, I know nuclear's "dirty little secrets". The reasons for the collapse of nuclear power systems include:
(1) Safety problems,
(2) Inability to dispose of nuclear waste. Obama now wants all nuclear waste stored at the power plant site and not Yucca Mountain.
(3) The potential uncontrolled proliferation of fissile materials in the hands of terrorists.
(4) Highest cost for generating electricity (14.5 cents/kWhr) of all fossil fuels and all of the renewable energy sources. (see www.IAEA.org)
(5) During the period 1985-2007, there was a huge cost escalation from $1 billion to more than $9 billion for the same size nuclear plant.
(6) The huge cost for retiring these "dinosaurs" is in the $ billions that will be passed on to the rate-payers

In the late '80s and early '90's, The Three-Mile Island, Chernobyl and the Monju breeder (Sea of Japan) nuclear incidents led the death knell of the nuclear industry. As serious as these problems are, they are secondary to a more fundamental failure of nuclear energy to establish itself as an economically competitive means of generating electricity. By taking into account the cost of uranium mining, processing, conversion to nuclear power rods, and waste disposal, there is only a net 3% margin over cost. However, with the Government subsidies, it was a little more profitable for the nuclear power companies. Thus, nuclear fission power is no longer an option.

Steven
Hopefully future planning will not involve shipping coal as it has already almost ruined our planet. Today's coal plants are about 30% efficient but if they are cleaned up they will be less than 20% efficient. How do we compare shipping endless trainloads of coal and blasting away mountaintops to a quiet, clean wire buried in the ground carrying wind, solar or geothermal energy? The choice seems pretty obvious to me regardless of cost.

Frank forgot to mention that our Govenor in his State of the State Address this week noted the desire and the need to open up the ROW to HVDC lines to connect the energy production capabilities of the north with the growing populations of the south and the rest of New England. I have not seen the details on this statement yet, but it is associated with future renewable energy production and power reliability.

"In addition, we need to connect Aroostook County's electric grid to the rest of Maine and New England. We can't continue with part of our State isolated from the rest. And while we need to be able to move quickly to review new projects when they are proposed, that doesn't mean relaxing our standards.
Every project must be judged on its details and must be right for Maine. But we must move forward.
We also must rethink the assets we have, and put them to the most efficient use. Right now in Maine, we have transportation corridors that run the length of our State. We need to transform them into much more.
Today I signed a Memorandum of Understanding with Bangor Hydro to explore the potential use of the right-of-way that exists along our interstates and roads for new, underground transmission lines.
Instead of a transmission company negotiating with hundreds of individual landowners and communities, they can utilize right-of-ways that already exist. There's less impact on the environment and less impact on people."

http://kennebecjournal.mainetoday.com/news/local/1067788517.html
(3/4 of the way down)

Tom:
Having read your post I have a question: would you think possible to have HVDC lines transporting solar power from northern africa to Europe? What could be a rough estimate costs of building a 50.000 MW HVDC line to link future solar fields of Morocco and Algeria to the European market through SPain?
And, would it be cheaper to produce electricity with Algerian gas and transfer it to EUrope through HVDC lines than actually producing the electricity in European gas fired stations?
Thanks

Tom,
Regarding your remark in comment 12, there are many reasons that the people of CA might have wanted to burn coal in Utah and transmit the electricity rather than build a new power plant and deal with the air pollution (especially given California's regulatory tendencies). Some of these factors might have tipped the balance in favor of transmission even if a pure energy cost argument does not. The energy costs you claims exist for transporting coal seem high....

Tom,
Having accepted that my uranium example was a counterexample to your claim, I was expecting that you would refine your argument for why transmitting electricity is more efficient than transporting coal. You still present no clear case for why this might be true (assuming that it is). Naturally, I agree that we need a major investment in transmission capacity and that HVDC has many advantages, but since you chose to make this particular efficiency point a part of your argument, I am still wondering if you can prove it....

Scott
Yes HVDC can be installed on existing AC towers and greatly reduce losses. It can be run on much smaller, lower towers also with only two conductors required. The right-of-way can be much narrower.

Are there circumstances in which you would recommend HVDC for use along existing above ground power rights of way (augmenting or replacing AC).

Also, I still occasionally hear claims that magnetic radiation from high tension lines is a significant health hazard for people living near lines. Do below ground and / or DC lines offer any advantages in that respect? And, are we ever likely to use HVDC in through densely populated ares, in any case.

Jim Tanner, I read your post, but am not sure what conclusions you want people to draw from it. It sounds to me as though you are saying that all modes of energy transmission entail some degree of risk, which I accept; but unless we stop using energy (which isn't going to happen), we still have to make some choices. Which choices are you advocating?

HVDC and AC each have a good purpose. HVDC seems best for long distances in remote areas while AC seems cost effective for comparitively short distances in populated places. Opposition to transmission of power across forested areas could be reduced if buried lines were used.

I also suggest the hybridization of wind and hydro as well as solar and hydro by recycling of the water coming from the base of the dam back into the storage area from wind and solar power sources. This might serve to shorten power transmission distances, have power transmission more in remote areas, increase power output of installed hydro systems and steady power output and serve as power storage for the renewable source. It would also serve to conserve water in the dam and minimize power reduction, especially during the dry season. If we have dams and transmission lines coming from dams, why not make better use of them.

I envision a coordinated energy system which could be tuned to integrate the best of the different energy sources together with the methods of energy storage and transmission. We should not consider electric transmission independent of energy generation and storage.

Steven
Certainly uranium is cheaper to ship than electricity. In fact, mines use so much electricity that they must be located near aa source of power.BHP Billiton Ltd.'s Olympic Dam mine in Australia uses 40% of the power in Southern Australia (690 MW) to make Uranium and Copper. They also use 690,000 liters of water per day from an ancient aquifer.
http://enochthered.wordpress.com/category/olympic-dam/
The Empire connection, which brings power down to New York city from the north was more economical than a gas pipeline connection alternative to local powerplants.
Another big plus for underground HVDC is security. Towers can easily be sabotaged by terrorists. A single bomb at the base of a transmission tower can knock a major link out for months.

I drove parts of the old Oregon Trail last year. I was surprised
that I only saw coal trains on that railroad.

Re: building ugly towers

I am sure Mr. Blakeslee's father did not come home from work smelling like creosote poles as mine did. Those poles carried electricity to west Texas oil fields. Being a kid, I did not recognize the greatness of the work performed by thousands of men from Texas to California in the 1950's.

Having helped build 3 power plants that are connected to urban centers by
"ugly towers" I invited him to attempt to take them down. The corporations that own them would have him before a judge pretty quick.

Re: following existing road and rail rights of way
We cannot have a truly long vision and assume that road and rail right-of-ways will remain static. Rail miles decreased as our interstate highway system increased. We cannot assume that underground HV electric lines will be any safer than underground gas lines where a backhoe operator
is injured every year. None of the gas lines that I helped build were free. The expense whether they went cross country or beside an existing highway
was monumental.

Safety: I cannot imagine an economical HV electrical line within 10 miles of a large population center that would be safe. There is too much construction, too much human activity, and too high a risk of vandalism to
really consider this proposition safe.

A pipeline company had a plane fly their lines regularly in Oklahoma over 20 years ago. One flight discovered a trailer house perched right on top of a 30 inch gas line. Can you imagine how many people would have died if that had been an HV electric line and the home owner had decided to drop in a septic tank? A short count would have been the whole family.

If it were not for corruption in gov. we would have used the Tesla DC transmission technology. He proved he had the best means of power transmission, so imagine all the savings and clean landscape and 95% less power outages we would now have if not for corruption. One thing that has not changed in all these years is the corruption in gov. lol

"New laws could make it easier and more profitable to build HVDC links and greatly reduce the cost of renewable energy."

Just because two statements exist in the same sentence does not make them related.

HVDC Lite from ABB and HVDC Plus from Siemens both provide connection at about 80KVDC and are economical at about 50 MW and 50 miles minimum size and length. They are used extensively by off-shore wind turbine facilities using submarine cables. The technology is available now to the wind developer who has the vision and wallet. And the courage to bury 80000 volt lines across the country side. Refitting bipolar and tripolar dc systems on existing 3 phase AC lines is also being employed and makes sense in certain places.

Lack of HVDC transmission would be a critical problem for offshore wind, wave or tidal systems. It is used more as an excuse for RE developers with a good wind or geothermal resource in a remote location and no market for their product.

Regarding this pasage of the text: "HVDC connection losses are only about 3% per 1000 km plus 1.5% for two voltage converters. This is much more efficient than conventional transportation. In fact HVDC can be often be justified because it is cheaper than building a pipeline to bring in gas to run power plants. Electric motor efficiencies are typically above 90% while fossil fuel engines are usually under 30% so it is more economical to ship electricity than fuel. 80% of rail shipping in the U.S. is for transporting fuel."

It is far from obvious that transmitting electricity is more efficient than transporting fuel. For instance, the energy cost for shipping uranium is very small and must be much less than the transmission losses on the electricity it could generate so it is still better to generate nuclear generated electricity near the point of use. Possibly the energy cost for shipping coal exceeds that for electricity transmission of the electricity the coal could generate, but one would not be able to conclude this from the information presented here.

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Thomas R Blakeslee’s books have been published in nine different languages. After serving for three years in the U.S. Navy, he earned a degree from CalTech in Pasadena, California in 1962. After working for IT&T in Antwerp, Belgium, he...